The inventive subject matter relates to electric power systems and methods of operating the same and, more particularly, to battery systems and methods of operating the same.
Uninterruptible power supply (UPS) systems a commonly used in applications such as data centers, where they are used to provide backup power in the event of the failure of a primary utility supply. In such applications, strings of valve-regulated lead-acid (VRLA) batteries are often used.
In such applications, VRLA batteries typically will be left in an idle state for extended periods of time, subject to trickle and/or periodic charging and intermittent testing. As such batteries may degrade over time, they may fail to provide rated voltage and/or current when called upon to provide power. Accordingly, data center operations often include regular battery inspection and maintenance to identify dead batteries or batteries that are perilously close to the end of their useful life. Such preventive maintenance can be time-consuming and expensive.
A variety of prognostic techniques have been developed to identify impending battery failure. Some of these techniques involve monitoring of battery parameters, such as output voltage, and determining battery status from this data. Examples of such techniques are described, for example, in U.S. Pat. No. 6,924,622 to Anbuky et al., U.S. Pat. No. 7,199,557 to Anbuky et al., and U.S. Patent Application Publication No. 2009/0228225 to Burgess.